Traveling sheet thickness changing method for cold tandem roller

ABSTRACT

Set values of a gauge-alteration-in-rolling amount after the next (i+1)-th stand and subsequent stands are modified, using the rolling results obtained when a leading end of a succeeding material passes through the i-th stand and the gauge results of the leading end portion of the succeeding material detected by the i-th stand outlet side gauge detector. The gauge results of the leading end of the succeeding material on the i-th stand outlet side is tracked up to the (i+1)-th stand, to thereby control the rolling speed of the i-th stand so as to make constant a mass-flow from the leading end of the succeeding material on the (i+1)-th stand inlet side. Thereby, the reverse off gauge caused at the succeeding stand, by turning on the AGC of the preceding stand, can be prevented and the gauge can be controlled to a desired value from the coil leading end portion.

This application is a 371 of PCT/SP98/03974 filed Sep. 4, 1998.

TECHNICAL FIELD

The present invention relates to a gauge-alteration-in-rolling methodof, when continuously rolling materials-to-be-rolled by a cold tandemrolling mill, altering set values from for the preceding material to forthe succeeding material, and more particularly, to agauge-alteration-in-rolling method in a cold tandem rolling mill, whichis capable of realizing a high accuracy in gauge immediately after thegauge-alteration-in-rolling point passing.

BACKGROUND ART

At the time of the gauge-alteration-in-rolling in the cold tandemrolling mill, generally a gauge-alteration-in-rolling amount (a rollgap-alteration amount and a rolling speed-alteration amount) of each ofthe stands is calculated in advance, during rolling a precedingmaterial, using an estimated rolling load value and an estimated forwardslip value, which are obtained by path schedules of the preceding andthe succeeding material, a set value of tension between stands, anestimated deformation resistance value, an estimated frictioncoefficient value, and the like.

On this occasion, there has been proposed a method of, when detectorsfor measuring the rolling results are available, modifying thegauge-alteration-in-rolling amount using thus obtained rolling results.

For example, there has been known a method of, when a gauge detector isprovided on an inlet side of the rolling mill, modifying the rollgap-alteration amount of a first stand using a mother material gaugemeasured by the inlet side gauge detector. Also, there has been known amethod of, when detectors for measuring the rolling load, the tensionbetween the stands, the rolling speed, and the stand outlet side gaugeare disposed at a preceding stand, modifying agauge-alteration-in-rolling amount at a succeeding stand using therolling results of the preceding stand detected by these detectors.

These methods intend for modifying, using the rolling results, thesetting errors of a gauge-alteration-in-rolling amount which resultsfrom various wrong estimation carried out for thematerials-to-be-rolled.

However, only modifying the gauge-alteration-in-rolling amount using themeasured mother material gauge like the former method disables thesetting errors resulting from difference in material property of thematerials-to-be-rolled, such as a deformation resistance error, to bemodified.

Further, according to the latter method of modifying thegauge-alteration-in-rolling amount of the succeeding stand using therolling results of the preceding stand, calculating the difference inmaterial property of the material-to-be-rolled by some methods using therolling results, and then modifying the gauge-alteration-in-rollingamount of the succeeding stand using the above calculated material-wiseerror causes the leading end portion of the succeeding material to becontrolled in gauge deviation, which, however, provides the followingproblems:

For example, when modifying, between the i-th stand and the next(i+1)-th stand, the gauge-alteration-in-rolling amount of the (i+1)-thstand using the results of the i-th stand, the gauge of the leading endportion of the succeeding material exposed at the (i+1)-th stand getsnearer to a desired value as shown by the arrow A in FIG. 7. However,when an AGC (automatic gauge control) of the i-th stand is turned onafter the gauge-alteration-in-rolling point B passes through the i-thstand, and hence the gauge deviation, resulting from the wrong settingat the time of the gauge-alteration-in-rolling at the i-th stand, getsnearer to a desired value as shown by the arrow C, the (i+1)-th standoutlet side gauge, which should get nearer to the desired value as shownby the arrow D unless there were no modification, shown by the arrow A,due to the rolling results of the i-th stand, comes off adversely fromthe leading end portion, as shown by the arrow E, due to themodification shown by the arrow A. This, until the AGC of the (i+1)-thstand is turned on and hence the (i+1)-th stand outlet side gaugereturns to the desired value as shown by the arrow F, reverselyincreases the gauge deviation, which undesirably provides the off gauge.

DISCLOSURE OF THE INVENTION

The present invention has been made in order to solve theabove-mentioned prior art problems. It is therefore an object of theinvention to realize a high accuracy in gauge immediately after thegauge-alteration-in-rolling point passing.

The present invention provides a gauge-alteration-in-rolling method ofaltering, when continuously rolling materials-to-be-rolled by the coldtandem rolling mill, altering set values from for a preceding materialto for a succeeding material, characterized in that modifying, using therolling result (a rolling load, a stand inlet and a stand outlet sidetension, a rolling speed, etc.) obtained when a leading end portion ofthe succeeding material passes through the i-th stand and the gaugeresults of the leading end portion of the succeeding material detectedby the i-th stand outlet side gauge detector, set values of agauge-alteration-in-rolling amount at the next (i+1)-th stand andsubsequent stands (a roll gap-alteration amount and a rollingspeed-alteration amount); and tracking the gauge results of the leadingend portion of the succeeding material on the i-th stand outlet side upto the (i+1)-th stand, to thereby control the rolling speed at the i-thstand so as to make constant a mass-flow from the leading end portion ofthe succeeding material on the (i+1)-th stand inlet side. This enablesthe above-mentioned problem to be solved.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram showing a method of modifying agauge-alteration-in-rolling amount using rolling results, which isproposed in Japanese Patent Application No. Hei 8-143066 by theapplicant;

FIG. 2 is a block diagram showing a state in which a leading endmass-flow-constant control is carried out according to the presentinvention;

FIG. 3 is a block diagram showing an arrangement of a control device,according to an embodiment, for carrying out the present invention;

FIG. 4 is a diagrammatic drawing showing a change state of the outletside gauge deviation at the time of the gauge-alteration-in-rolling whenthe gauge-alteration-in-rolling is performed by the conventional method;

FIG. 5 is a diagrammatic drawing showing an example of a change state ofthe outlet side gauge deviation at the time of thegauge-alteration-in-rolling when the calculation to modify thegauge-alteration-in-rolling amount proposed in Japanese PatentApplication No. Hei 8-143066 is performed;

FIG. 6 is a diagrammatic drawing showing an example of a change state ofthe outlet side gauge deviation at the time of thegauge-alteration-in-rolling when the present invention is carried out;and

FIG. 7 is a diagrammatic drawing useful in explaining the problemoccurring on the conventional gauge-alteration-in-rolling method.

BEST MODE FOR CONDUCTING THE INVENTION

An embodiment of the present invention will be described hereinafterwith reference to the drawings.

In an embodiment of the present invention as shown by the FIG. 1, when aleading end portion of a succeeding material 12 is gripped into the i-thstand, detectors such as a load detector 20 i and a tension detector 22i of the i-th stand collect rolling load results, a stand inlet andoutlet side tension results, rolling speed results, and the like, andalso collect gauge results obtained when the result collecting pointreaches an gauge detector 24 i on the i-th stand outlet side. Then, aload ratio Zpk of the leading end portion of the succeeding material islearned as a learning coefficient by the use of the following equation:

 Zpk=Pact/Pcal  (1)

where Pact is a rolling load result value of the i-th stand, and Pcal isa calculated value of a rolling load obtained by the use of a rollingload equation according to the tension, the speed, the gauge results,and the like.

Supposing that the influence of the change of the friction coefficientfor the coil leading end portion on the rolling load is small, thelearning coefficient Zpk is used as an index representing an estimateddeformation resistance error of the material. Namely, theabove-mentioned learning coefficient Zpk obtained by the use of theequation (1) at the i-th stand is multiplied to a succeeding materialload-estimating equation of the (i+1)-th stand and subsequent stands, soas to modify a set value of the gauge-alteration-in-rolling amount ofthe (i+1)-th stand and subsequent stands (e.g. a roll gap amount ΔSi+1,ΔSi+2, and a rolling speed-alteration amount ΔVi+1, ΔVi+2), and then theobtained value is output to a control device.

In FIG. 1, reference numeral 10 designates a preceding material, 24 i 1a gauge detector on the i-th stand inlet side, 22 i 1 a tension detectoron the i-th stand inlet side, 20 i+1 a load detector on the (i+1)-thstand, 20 i+2 a load detector on the (i+2)-th stand, and 22 i+1 atension detector on the (i+1)-th stand outlet side.

The above-mentioned gauge-alteration-in-rolling amountmodification-calculation, which has been proposed in Japanese PatentApplication No. Hei 8-143066 by the applicant, is preferably carried outon all the downstream side stands, since it reflects the hardness of thestrip.

On the other hand, according to the above method, although thegauge-alteration-in-rolling amount re-calculation using the resultsmakes the gauge of the leading end portion of the succeeding material atthe (i+1)-th stand into a desired value as described with reference toFIG. 7, until the AGC of the (i+1)-th stand is turned on after the AGCof the i-th stand has been turned on, the off gauge reversely occurs atthe (i+1)-th stand outlet side as described above.

Therefore, in order to solve the problem, according to the presentinvention, as shown in FIG. 2, the i-th stand outlet side gauge resultsof the leading end portion of the succeeding material detected at thegauge detector 24 i on the stand outlet side is locked on when they arecollected for the purpose of the gauge-alteration-in-rolling amountre-calculation, and then the gauge results obtained after the resultshave been collected are tracked up to the (i+1)-th stand. Then, when thetracking point reaches the (i+1)-th stand, the rolling speed Vi of thei-th stand is controlled so as to make constant a mass-flow from thecoil leading end portion (lock-on point) on the (i+1)-th stand inletside, as shown in the following equation:

ΔVi/Vi=(hi,L/Hi+1)−1  (2)

where ΔVi/Vi designates a rolling speed-alteration amount of the i-thstand, hi,L a lock-on value of the i-th stand outlet side gauge resultof the coil leading end portion, Hi+1 a value of the (i+1)-th standinlet side gauge results obtained by tracking the output of the gaugedetector on the i-th stand outlet side 24 i up to the (i+1)-th stand.

In FIG. 2, M designates a mill motor of the i-th stand.

A control in FIG. 2 (referred to as “the leading end portionmass-flow-constant control”) is carried out until thegauge-alteration-in-rolling is finished and then each of the AGC startscontrolling. The leading end portion mass-flow-constant control is foreliminating the gauge deviation, which requires the control by only asingle stand just thereunder.

In this way, the wrong setting of the gauge-alteration-in-rolling amountat the time of the gauge-alteration-in-rolling can be modified using therolling results by modification-calculating thegauge-alteration-in-rolling amount which is the same as Japanese PatentApplication No. Hei 8-143066, and the off gauge occurring by the AGCturning on at the preceding stand is prevented at the next stand by theleading end portion mass-flow-constant control characterizing thepresent invention, which enables the gauge to be controlled to a desiredvalue from the coil leading end portion.

Referring now to FIG. 3, there is shown an embodiment of a controldevice for carrying out the present invention. This embodiment comprisesa state-measuring section 30 i, 30 i+1, 30 i+2, . . . , and a controldevice 32 i, 32 i+1, 32 i+2, . . . for each of the stands.

A load model 34 receives state signals, such as an inlet gauge Hi, anoutlet gauge hi, a rolling load Pi, a backward tension Tbi, a forwardtension Tfi, a rolling speed Vi, which are obtained by thestate-measuring section 30 i, and then calculates a rolling load Pi,calby the use of a rolling load equation.

Also, a signal of the gauge-alteration-in-rolling point passing throughthe i-th stand, which is obtained by the state-measuring section 30 i,causes the then outlet gauge hi to be stored in a leading end portiongauge-storing section 36, and then to be tracked at a gaugedata-tracking section 38.

A load-calculated value Pi,cal obtained by the load model 34, and a loadresult value Pi,act obtained at the state-measuring section 30 i areinput to a gauge-alteration-in-rolling amount modification-calculatingsection 40, which calculates the leading end portion load ratio Zpk bythe use of the equation (1), and then calculates the set values of thegauge-alteration-in-rolling modification amount ΔS, ΔV (in the same asJapanese Patent Application No. Hei 8-143066).

Furthermore, a leading end portion mass-flow-constant control section 42for carrying out the leading end portion mass-flow-constant control,which characterizes the present invention, is turned on when thegauge-alteration-in-rolling point passes through the (i+1)-th stand, andthen calculates the i-th stand roll speed modification amount ΔVi by theuse of the above-mentioned equation (2) according to the leading endportion the i-th stand outlet gauge result lock-on value hi,L input fromthe leading end portion gauge storing section 36, and the (i+1)-th standinlet gauge result value Hi+1, obtained by tracking the i-th standoutlet result value hi, input from the gauge data-tracking section 38.The calculated value is output to the control device 32 i of the i-thstand mill motor and so on.

The control by the leading end portion mass-flow-constant controlsection 42 is turned off by the signal transmitted from e.g. thestate-measuring section 30 i+2, at the timing (variable) when the AGCcontrol of the (i+1)-th stand is turned on.

According to the embodiment, the method of the present invention isapplied to the first stand in a five-stand-type continuous rolling mill,thereby causing the gauge-alteration-in-rolling amount of the secondstand and subsequent stands to be corrected.

There is shown in FIG. 4 a change state of the deviation of the firststand outlet gauge and the third stand one (in place of the second standoutlet gauge detector which is not provided) in the case of thegauge-alteration-in-rolling according to a conventionalgauge-alteration-in-rolling method (referred to as “the conventionalmethod”) which carries out no gauge-alteration-in-rollingmodification-calculation using the rolling results. There is shown inFIG. 5 a change state in which the rolling speed modification using theequation (2) is not carried out although the gauge-alteration-in-rollingamount of the next stand and subsequent stands are modified using therolling results as is the case with the former application (referred toas “the comparison method”). There is shown in FIG. 6 a case in whichthe gauge-alteration-in-rolling is carried out according to the methodof the present invention.

As apparent from FIG. 4, according to the conventional method, the gaugedeviation occurring on the first stand remains up to the third stand.Also, according to the comparison method, the gauge deviation of thecoil leading end portion occurring on the first stand due the wrongsetting of the gauge-alteration-in-rolling amount is modified at thesecond stand; however, the AGC of the first stand is turned on, and thenas the first stand outlet side gauge gets nearer to the desired value,the gauge deviation reversely increases at the third stand. Over againstthese, according to the present invention, as apparent from FIG. 6, thecoil leading end portion gauge becomes a desired value at the secondstand, and then the second stand outlet gauge is controlled by the useof the equation (2), which enables the gauge to be controlled to thedesired value from the coil leading end portion.

CAPABILITY OF EXPLOITATION IN INDUSTRY

The reverse off gauge which occurs when the AGC of the preceding standis turned on, is prevented from occurring on the succeeding stand, whichenables the gauge to be controlled to the desired value from the coilleading end portion.

What is claimed is:
 1. A method of altering settings forgauge-alteration-in-rolling amounts from set values for a precedingmaterial to set values for a succeeding material when continuouslyrolling materials in a cold tandem rolling mill, comprising: obtainingrolling results for a succeeding material when a leading end portion ofthe succeeding material passes through an i-th stand and gauge resultswhen the leading end portion of the succeeding material passes through agauge detector at an outlet side of the i-th stand; modifying settingsfor a gauge-in-alteration-rolling mount at an (i+1)-th stand andsubsequent stands, using the rolling results obtained when the leadingend portion of the succeeding material passes through the i-th stand andusing gauge results of the leading end portion of the succeedingmaterial detected by the gauge detector at the outlet side of the i-thstand; and tracking the gauge results for the leading end portion of thesucceeding material from the gauge detector at the outlet side of thei-th stand to an inlet side of the (i+1)-th stand, to thereby controlthe rolling speed at the i-th stand and make constant a mass-flow fromthe leading end portion of said succeeding material on the inlet side ofthe (i+1)-th stand.
 2. A method of altering settings forgauge-alteration-in-rolling amounts, as set forth in claim 1, whereinthe rolling results obtained when the leading end portion of thesucceeding material passes through the i-th stand include at least oneof a rolling load, a tension at an inlet side of a stand and a tensionat an outlet side of a stand, and a rolling speed.
 3. A method ofaltering settings for gauge-alteration-in-rolling amounts, as set forthin claim 1, wherein a setting of the gauge-alteration-in-rolling amountat the (i+1)-th stand and the subsequent stands includes at least one ofa roll gap-alteration amount and a rolling speed-alteration amount.
 4. Amethod of altering settings for gauge-alteration-in-rolling amounts, asset forth in claim 3, wherein the setting for thegauge-alteration-in-rolling amount is calculated, during rolling of apreceding material, using an estimated rolling load and an estimatedforward slip value obtained by path schedules of the preceding materialand the succeeding material, a setting for tension between stands, anestimated deformation resistance value, and an estimated frictioncoefficient.
 5. A method of altering settings forgauge-alteration-in-rolling amounts, as set forth in claim 1, whereinthe settings for the gauge-alteration-in-rolling amount at the (i+1)-thstand and the subsequent stands is modified by: learning a load ratio,Pact/Pcal, where Pact is a rolling load measured at the i-th stand andPcal is a calculated value of a rolling load obtained by the use of arolling load equation, for the leading end portion of the succeedingmaterial as a learning coefficient using the rolling results and thegauge results at the outlet side of the i-th stand; and multiplying aload-estimating equation for the succeeding material at the (i+1)-thstand and the subsequent stands by the learning coefficient obtained atthe i-th stand as an index representing an estimated deformationresistance error of the material.
 6. A method of altering settings forgauge-alteration-in-rolling amounts, as set forth in claim 1, wherein acontrol to keep mass flow constant from the leading end portion of thesucceeding material is maintained until the gauge-alteration-in-rollingis finished and an automatic gauge control is started at the (i+1)-thstand.